1. Fields of the Invention
The present invention relates to a ratchet wrench, and more particularly, to a ratchet wrench having a restriction member in the same room with the pawl which is restricted by the restriction member to ensure that the pawl is moved under control.
2. Descriptions of Related Art
The conventional ratchet wrench as disclosed in FIG. 13 and comprises a head 91, a ratchet wheel 92, a pawl 93, a resilient member 94 and a clip 96. The head 91 has a first room 911 defined therethrough and a flange extends from the lower inner periphery of the first room 911. A second room 912 is defined in the inner periphery of the first room 911. The second room 912 has a closed top and a closed bottom. The first room 911 has a first groove 913, and the second room 912 has a recess 914 defined in the inner periphery thereof. The ratchet wheel 92 is rotatably received in the first room 911 and has an engaging portion 921 on the outer periphery thereof. A mounting portion 922 is defined through the top and the bottom of the ratchet wheel 92. The ratchet wheel 92 has a second groove 923 which is located corresponding to the first groove 913. The pawl 93 is received in the second room 912 and has multiple engaging teeth 931 on the front thereof. The resilient member 94 is located in the recess 914 and biased between the inner end of the recess 914 and the rear side of the pawl 93 so as to engage the engaging teeth 931 with the engaging portion 921 of the ratchet wheel 92. The clip 96 is engaged with the first and second grooves 913, 923.
However, as disclosed in FIGS. 14 to 16, when the head 10 is rotated counter clockwise to push the pawl 92 away from the pawl 93, because the volume of the pawl 93 is about 3/10 of the volume of the second room 912, there is a space available for the pawl 92 to move within the second room 912. Therefore, the pawl 93 is driven by the rotation of the ratchet wheel 92 and moves a distance that is more than needed, this causes the head 91 together with the ratchet wheel 92 to rotate freely. Besides, the inclined recess 914 is difficult to be drilled.
U.S. Pat. No. 7,444,901 discloses a ratchet wrench comprising a wrench body having an end portion provided with a mounting hole and a receiving chamber connected to the mounting hole. A ratchet wheel is mounted in the mounting hole of the wrench body and has an outer wall provided with a plurality of ratchet teeth. A pawl member defines a top surface and a bottom surface mounted in the receiving chamber of the wrench body having a first side including a first end provided with a plurality of locking teeth extending from the top surface to the bottom surface engaged with the ratchet teeth of the ratchet wheel successively and completely and a second end provided with a sliding face extending from the top surface to the bottom surface slidable on the ratchet teeth of the ratchet wheel. The first and second ends define a whole circumferential length of the first side of the pawl member. An elastic member is mounted in the receiving chamber of the wrench body and biased between the peripheral wall of the receiving chamber of the wrench body and a second side of the pawl member to push the pawl member toward the ratchet wheel. The elastic member is located adjacent to the sliding face of the pawl member and the sliding face of the pawl member is located between the elastic member and the locking teeth of the pawl member. The first side of the pawl member is a concave surface which extends through the whole circumferential length of the first side of the pawl member. The sliding face of the pawl member is a concave recessed smooth surface which extends successively and completely through a circumferential length of the second end of the first side of the pawl member that is half of the circumferential length of the first side of the pawl member. The pawl member is movable relative to the ratchet wheel between a first position where all of the locking teeth of the pawl member are engaged with the ratchet teeth of the ratchet wheel closely and completely, and the sliding face of the pawl member evades the ratchet teeth of the ratchet wheel, and a second position where all of the locking teeth of the pawl member are disengaged from the ratchet teeth of the ratchet wheel, and the sliding face of the pawl member is movable on the ratchet teeth of the ratchet wheel.
In order to restrict the movement of the pawl member in the receiving chamber, the volume of the pawl member is slightly smaller than the volume of the receiving chamber. In other words, the pawl member has to be made big enough to meet the above mentioned requirement. However, the pawl member is made by way of powder injection, so that the larger volume of the pawl member, the higher cost is involved. Therefore, there is a room to be improved.
The present invention intends to provide a ratchet wrench to eliminate the shortcomings mentioned above.